Fricke-Begemann T, Burke J
Appl Opt. 2001 Oct 1;40(28):5011-22. doi: 10.1364/ao.40.005011.
An electronic speckle interferometer, arranged for out-of-plane sensitivity and with an off-axis reference beam to produce spatial phase bias, is used for three-dimensional deformation field measurements. The complex amplitude of the object wave is calculated by application of a Fourier-transform method to a single interferogram. The change in phase after object deformation yields the out-of-plane component of the displacement field. The two in-plane components are obtained by cross correlation of subimages of the reconstructed object wave's intensity, a method that is also referred to as digital speckle photography. The Fourier-transform algorithm is extended and modified, leading to random measurement errors that are below widely accepted theoretical limits and also to an extended measuring range. These properties and the mutually combined information improve the accuracy of both methods compared with their usual single implementation. The performance is evaluated in experiments with pure out-of-plane, pure in-plane, and combined deformations and compared with theoretical values. An example of a practical application is given.
一种用于面外灵敏度且具有离轴参考光束以产生空间相位偏置的电子散斑干涉仪，用于三维变形场测量。通过将傅里叶变换方法应用于单个干涉图来计算物波的复振幅。物体变形后的相位变化产生位移场的面外分量。通过对重建物波强度的子图像进行互相关来获得两个面内分量，该方法也称为数字散斑摄影。对傅里叶变换算法进行了扩展和修改，导致随机测量误差低于广泛接受的理论极限，并且测量范围也得到了扩展。与通常的单一实现方式相比，这些特性以及相互组合的信息提高了两种方法的精度。在纯面外、纯面内和组合变形的实验中评估了该性能，并与理论值进行了比较。给出了一个实际应用的例子。
